FREE BOOKS

Author's List




PREV.   NEXT  
|<   20   21   22   23   24   25   26   27   28   29   30   31   32   33   34   35   36   37   38   39   40   >>  
s, according as the globe may be devided two waies, either cutting quite through by the meridian from North to South, as if you should cut an apple by the eye and the stalke, or cutting it through the AEquinoctiall, East and West, as one would divide an apple through the midst, betweene the eye & the stalke. The former makes two faces, or hemispheares, the East and the West hemispheare. The latter makes likewise two Hemispheares, the North and the South. Both suppositions are good, and befitting the nature of the globe: for as touching such vniversall maps, wherein the world is represented not in two round faces, but all in one square plot, the ground wherevpon such descriptions are founded, is lesse naturall and agreeable to the globe, for it supposeth the earth to be like a Cylinder (or role of bowling allies) which imagination, vnlesse it be well qualified, is vtterly false,[2] and makes all such mappes faulty in the scituation of places. Wherefore omitting this, we will shew the description of the two former only, both which are easie to be done. [Footnote 2: Of this Hypothesis see _Wrights_ errors of navigation.] 1 To describe an AEquinoctiall planispheare, draw a circle (_ACBD_) and inscribe in it two diameters (_AB_) & (_CD_) cutting each other at right angles, and the whole circle into foure quadrants: each whereof devide into 90. parts, or degrees. The line (_AB_) doth fitly represent halfe of the AEquator, as the line (_CD_) in which the points (_C_) & (_D_) are the two poles, halfe of the Meridian: for these circles the eye being in a perpendicular line from the point of concurrence (as in this projection it is supposed) must needs appeare streight. To draw the other, which will appeare crooked, doe thus. Lie a rule from the Pole (_C_) to every tenth or fift degree of the halfe circle (_ADB_) noting in the AEquator (_AB_) every intersection of it and the rule. The like doe from the point (_B_) to the semicircle (_CAD_) noting also the intersections in the Meridian (_CD_) Then the diameters (_CB_) and (_AB_) being drawne out at both ends, as farre as may suffice, finding in the line (_DC_) the center of the tenth division from (_A_) to (_C_) and from (_B_) to (_C_), & of the first point of intersection noted in the meridian fr[~o] the AEquator towards (_C_) by a way familiar to Geometricians connect the three points, and you haue the paralell of 10. degrees from the AEquator: the like must bee done in
PREV.   NEXT  
|<   20   21   22   23   24   25   26   27   28   29   30   31   32   33   34   35   36   37   38   39   40   >>  



Top keywords:

AEquator

 

circle

 

cutting

 

intersection

 

appeare

 
Meridian
 

degrees

 

points

 
noting
 

diameters


AEquinoctiall

 

stalke

 

meridian

 
streight
 

crooked

 
vniversall
 

projection

 

supposed

 
devided
 

degree


concurrence

 

represented

 

touching

 

represent

 

perpendicular

 

circles

 

familiar

 

Geometricians

 
paralell
 

connect


division

 
center
 

intersections

 

semicircle

 

drawne

 

finding

 

suffice

 

nature

 

mappes

 

faulty


scituation

 

qualified

 

vtterly

 
places
 

Wherefore

 

description

 
omitting
 
Hemispheares
 

vnlesse

 

agreeable